Module mod_auth_db

Summary

This module provides an alternative to DBM files for those systems which
support DB and not DBM. It is only available in Apache 1.1 and
later.

On some BSD systems (e.g., FreeBSD and NetBSD) dbm
is automatically mapped to Berkeley DB. You can use either mod_auth_dbm or mod_auth_db. The
latter makes it more obvious that it's Berkeley DB. On other
platforms where you want to use the DB library you usually have
to install it first. See http://www.sleepycat.com/
for the distribution. The interface this module uses is the one
from DB version 1.85 and 1.86, but DB version 2.x can also be
used when compatibility mode is enabled.

The AuthDBGroupFile directive sets the name of a DB file
containing the list of user groups for user authentication.
File-path is the absolute path to the group file.

The group file is keyed on the username. The value for a
user is a comma-separated list of the groups to which the users
belongs. There must be no whitespace within the value, and it
must never contain any colons.

Security: make sure that the AuthDBGroupFile is stored
outside the document tree of the web-server; do not
put it in the directory that it protects. Otherwise, clients
will be able to download the AuthDBGroupFile unless otherwise
protected.

Combining Group and Password DB files: In some cases it is
easier to manage a single database which contains both the
password and group details for each user. This simplifies any
support programs that need to be written: they now only have to
deal with writing to and locking a single DBM file. This can be
accomplished by first setting the group and password files to
point to the same DB file:

AuthDBGroupFile /www/userbase
AuthDBUserFile /www/userbase

The key for the single DB record is the username. The value
consists of

Unix Crypt-ed Password : List of Groups [ : (ignored)
]

The password section contains the Unix crypt() password as
before. This is followed by a colon and the comma separated
list of groups. Other data may optionally be left in the DB
file after another colon; it is ignored by the authentication
module.

The AuthDBUserFile directive sets the name of a DB file
containing the list of users and passwords for user
authentication. File-path is the absolute path to the
user file.

The user file is keyed on the username. The value for a user
is the crypt() encrypted password, optionally followed by a
colon and arbitrary data. The colon and the data following it
will be ignored by the server.

Security: make sure that the AuthDBUserFile is stored
outside the document tree of the web-server; do not
put it in the directory that it protects. Otherwise, clients
will be able to download the AuthDBUserFile.

Important compatibility note: The implementation of
"dbmopen" in the apache modules reads the string length of the
hashed values from the DB data structures, rather than relying
upon the string being NULL-appended. Some applications, such as
the Netscape web server, rely upon the string being
NULL-appended, so if you are having trouble using DB files
interchangeably between applications this may be a part of the
problem.

A perl script called
href="../programs/dbmmanage.html">dbmmanage is included with
Apache. This program can be used to create and update DB format
password files for use with this module.

Setting the AuthDBAuthoritative directive explicitly to
'off' allows for both authentication and
authorization to be passed on to lower level modules (as
defined in the Configuration and
modules.c file if there is no
userID or rule matching the supplied
userID. If there is a userID and/or rule specified; the usual
password and access checks will be applied and a failure will
give an Authorization Required reply.

So if a userID appears in the database of more than one
module; or if a valid Require directive applies to
more than one module; then the first module will verify the
credentials; and no access is passed on; regardless of the
AuthAuthoritative setting.

A common use for this is in conjunction with one of the
basic auth modules; such as mod_auth.c. Whereas this
DB module supplies the bulk of the user credential checking; a
few (administrator) related accesses fall through to a lower
level with a well protected .htpasswd file.

By default, control is not passed on and an unknown userID
or rule will result in an Authorization Required reply. Not
setting it thus keeps the system secure and forces an NCSA
compliant behavior.

Security: Do consider the implications of allowing a user to
allow fall-through in his .htaccess file; and verify that this
is really what you want; Generally it is easier to just secure
a single .htpasswd file, than it is to secure a database which
might have more access interfaces.